The embodiments described herein relate generally to gait modulation systems, and more particularly, to a functional electrical stimulation (FES) orthosis for gait modulation and methods of using the same.
It is known that pathologies of the neuromuscular system due to disease or trauma to the central nervous system, such as for example, stroke, spinal cord injury, head injury, cerebral palsy, and multiple sclerosis can impede limb function of the arms or legs (or portions thereof). Gait, the biomechanical description of walking, can suffer static and dynamic parameter variations due to neuromuscular impairments, which cause non-symmetrical walking, reduced walking speed, and reduced walking stability. For example, drop foot describes a gait attributable to weak or uncoordinated activation of the ankle dorsiflexors due to disease or trauma to the central nervous system. Patients suffering from drop foot tend to drag the foot during the swing phase of walking and usually try to compensate for this dragging by hiking the corresponding hip or swinging the corresponding leg in a circular motion. These patients tend to have reduced stability, are prone to frequent falls, and their walking movements are unaesthetic and energy consuming.
Limb muscles, however, can generally be activated with functional electrical stimulation (FES). In FES, precisely timed bursts of short electrical pulses (e.g., from a neuroprosthetic, an FES orthosis, and/or the like) are applied to motor nerves to generate muscle contraction, which can be applied to enhancing limb function. Although neuroprosthetic systems are known, some such systems suffer from drawbacks that prevent the systems from being widely used by potential patients. For example, in instances in which stroke or brain injury results in problems with arm movement or gait, such problems are often accompanied by hand impairment on the same side of the body as the problematic limb. Thus, donning an FES orthosis is often carried out using solely the contra-lateral, unaffected hand. Moreover, the posture of the plegic limb is often problematic, especially in cases where spasticity results in reduced voluntary movements and/or limited passive range of motion of the limb joints. Consequently, objective biomechanical problems exist in donning some known orthotic devices as well as locating the electrodes in exact positions onto the limb, which is essential for activating the desired movement pattern. As such, some known neuroprosthetic devices fail to enable facile, quick, and accurate donning of the device by an impaired patient using a single hand, and particularly, when the least effected hand is shaky or otherwise unstable.
FES devices typically utilize a stimulator unit to create and control the electrical pulses being applied to motor nerves that is physically separate from the FES orthosis. The external stimulator unit, which is connected to the FES orthosis by several electrical wires, is located on the body of the user and/or is otherwise worn by the user. These devices can be inconvenient for the user. Specifically, the wiring, which is usually arranged to run along the leg under the clothing to connect the device components, can be difficult to operate, cumbersome and uncomfortable.
In other instances, an FES orthosis can be a self-contained device. For example, some known orthoses can include a stimulator unit coupled to a narrow band that is made of a thermoplastic material, which is molded to the limb anatomy of an individual user by heating and softening the thermoplastic material and subsequently fitting the band to the contour of the underlying limb segment. Thus, the shape and size of the device and the electrode positioning is custom-fitted to the leg of one user and individualized for the user. This procedure is carried out by a medical professional trained, for example, to accurately identify the stimulation points that cause contraction of the muscles, positioning and locking the electrodes thereto.
Activation of the leg muscles by electrical stimulation typically includes transferring high stimulation currents through one or more electrodes to the skin surface of the patient, which activates skin sensory receptors in addition to underlying excitable motor nerve and muscle tissue. As a result, the intensity of sensory activation often depends on the intensity of the current density passing through the skin surface. The level of muscle activation, therefore, is often limited to the patient's individual tolerance to activation of such skin pain sensors. Thus, the stimulation parameters of the device are adjusted for each patient, which can be time consuming and often includes attaching the orthosis to a control device via wires.
Therefore, a need exists for improved systems and apparatus for a neuroprosthetic system that can be easily and accurately donned on the limb by patient and that includes a stimulation unit that can be remotely controlled and/or adjusted.